EFI: PowerTuner Maps vs. A/F ratio

breaking news from my freeway test session ride:

- around the block you can test the lower left map point only; that'll be coasting in 5th doing a steady 50mph


- you can't test drive a map within city limits, you'll always read "rich" when glancing at the meter thanks to some throttle wick fuel addon mechanism


- on the freeway, especially on a substantial hill, "all sevens" is lean at WFO from 40 till 100 mph, you'll hear the pinging! :jawdrop: (but okay I had the iginition still advanced!)


- as an immediate countermeasure I retarded ignition from my stupid +2 to late -4 :facepalm:

  no more pinging, piston saved, but no more power as well, but that was to be expected


- next thing I did was crawl to rich on all full throttle map points,

 (top row, easy job: facing looong freeway hill, in top gear whack throttle WFO going 40mph and wait)


- next was checking 1/8h throttle maps points for avoidance of lean at higher rpms,

 e.g. making sure even in thrid(!) gear going downhill at gazillion rpms I'd be a tad on the rich side


the resulting fuel map for the non pea shooter exhaust tip:

-5 -5 -5

-7 -7 -6

-4 -4 -3



- the -4 in the lower left still is lean when coasting at 1/8th throttle. I'll leave it there, saves fuel and keeps the exhaust clean.

- the hardest to dial in is "medium throttle", I'm not sure if these -7s really run rich :devil:

- with that map you only see "lean" at very low throttle opening and low to medium rpm, anything else reads "rich"


Considering my eariler calculations that max. power (A/F 12,5) needs 16% more fuel than an A/F of 14,7 :goofy:

and remembering that one step in PowerTuner fuel map is 3% acc. to YAMAHA (manual and video)

one needs to PowerTune to 5,3 (16%/3%) steps richer that perfect A/F, it apperas that

PowerTuner fuel=0 already is the max. power A/F ratio, for my bike and exhaust and ....

Good job YAMAHA :thumbsup:

(rationale: with the -5 in the WFO row of the fuel map I didn't see "lean" anymore,

 with -6 in WFO row there were lean occasions,

 so these 5,3 steps richer than perfect A/F ratio lead directly to "0" as map value)

Edited by WRF-Rowdy

I had a carbed bike that had way better throttle response with a fat pilot but it would suck down the gas.  Maybe because it was a simple carb with no accelerator pump.


I never bothered to get my Wr400f or WR450F accelerator pumps to behave, because they are no use on tarmac:

When you - errornously - open the throttle too much for current rpms, the pump might be able to compensate

while it is spraying, and then? 

Afterwards on loose ground you might either be chopping the throttle anyhow or the rear is spinning (rpms much higher)

but on tarmac you might be going 3 mph faster hence it'll bog right when the pumps stops spraying.


My solution was: learn proper throttle control and you don't need no stinking acc. pump.

A buddy of mine was disabling his pump even while racing.


But I do agree with you that a rich pilot jet helps a lot. In winter I'd ride a 48. Some summers I did remember to swap it for the 45,

other summers I left the 48 in.

Edited by WRF-Rowdy

the resulting fuel map for the non pea shooter exhaust tip:

-5 -5 -5

-7 -7 -6

-4 -4 -3



What's the ignition map look like?

What's the ignition map look like?


"piston protection mode": all set to -4 (e.g. very late ignition)

If you run these lean fuel numbers, you wil cause knocking (ping ping ping) with positive ignition values like +2


But that is a valid question , I'll try and see how/if all zeroes work with that weird map, stay tuned, will take 15 mins. ;)



on the inner city 3 lane hillclimb, WFO was ok, but,

I think I heard one or two pings, when slightly backing off from full WFO.

Might be these -7 in the mid throttle row, that could be too lean for an ignition advance of +-0.

The rest of WFO, especially down at low rpms did fare well, no pinging to be noticed.


But that map is my current best try "A/F 14.7" map.

Except for low throttle values I won't ride with that map for the upcomming years.

I'm not doing that for emissions purposes, mind you, I just wanted to know what

A/F certain PowerTuner fuel adjustemt values are resulting in.


I estimated I'll run something like three zeroes in top row,

play some more with the mid throttle row,

and leave to lean bottom row as it is, hoping for noticeable fuel savings

when not riding in "knive between teeth" mode.

Edited by WRF-Rowdy

I tried adding fuel in that cell but it doesn't help all that much.  I figure I might as well save the fuel if it's gonna pop annyway.

Closed throttle is sadly not reachable via PowerTuner, not at all.  That is what the FI-diagnostic tool's CO setting is doing:

When I went from -4 to -24 the hissing and hickupping and occassional popping did noticable increase.

I've not decided yet if I'll go back to -4 ish.  It did start very well in gear with that mixture, and more

hising and popping yust to run a niver A/F ratio is a rather odd goal for me.

It really only pops on decel with the throttle closed from a range about 3500-3000 rpms.  I don't have the resolution to target that one little spot.  No big deal I guess. 

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